1. Field of the Invention
The present invention relates to an oil supply apparatus for a linear compressor, and more particularly to an oil supply apparatus for a linear compressor which reduces the number of valves which control suction and discharge of an oil, thereby enabling fabrication and assembly thereof, and supplying an oil of an adequate amount to friction areas of driving elements.
2. Description of the Conventional Art
As generally well known, a linear compressor compresses a refrigerant by reciprocating a piston in a cylinder using a magnet and a coil, instead of a crank shaft.
FIG. 1 illustrates a conventional linear compressor. As shown therein, the conventional linear compressor includes a compressor unit 10 horizontally provided in a hermetic vessel C having a predetermined shape and sucking, compressing, and discharging a refrigerant, and an oil supply unit 20 disposed at an outer side of the compressor unit 10 and supplying an oil to friction areas of driving elements of the compressor.
More particularly, in the compressor unit 10 there are provided a cylinder 12 connected with a stator 11a (inner and outer laminations) as a single body and a piston 13 which is connected with a rotor (including a magnet) 11b of a linear motor 11 and reciprocates into the cylinder 12.
The oil supply unit 20, as shown in FIG. 2, consists of an oil supply pipe 21 disposed at an outer side of the compressor unit 10, a suction cover 22 engaged with an end of the oil supply pipe 21 at an oil suction side and having a suction inlet 22a at a bottom thereof, and a discharge cover 23 engaged with the other end of the oil supply pipe 21 at an oil discharge side and connected to one side of the compressor unit 10.
Further, in the oil supply pipe 21, there are provided a mass 24 in which there is formed a first oil path 24a communicating with the suction cover 22 and the discharge cover 23, respectively, the mass sucking and discharging the oil which is moved by the reciprocation of compressor unit 10 and placed at a bottom of the hermetic vessel C, first and second compression coil springs 25A, 25B, respectively connected between both ends of the mass 24 and ends of inner surfaces of both sides of the oil supply pipe 21, a suction valve 26 which is connected with an end of the first compression coil spring 25a and in contact with an inner surface of the suction cover 22, thereby allowing or blocking the flow of the oil which flows thereinto through the suction opening 22a formed at the bottom of the suction cover 22, and a discharge valve 27 which is connected with an end of the second compression coil spring 25b and in contact with an end portion of an oil discharge side of the mass 24, thereby allowing or blocking the flow of the oil which has passed through the first oil path 24a.
As shown in FIG. 3, the suction valve 26 and the discharge valve 27 are respectively formed in a scroll type, in which opening/closing units 26a, 27a are provided in each center thereof.
Now, the operation of the conventional linear compressor will be described with reference to the accompanying drawings.
When an electric current is applied to the linear motor 11, the rotor 11b linearly reciprocates and accordingly the piston 13 reciprocates in the cylinder 12. As the piston 13 reciprocates in the cylinder 12, the refrigerant gas flowing into the hermetic vessel C is sucked into a compression chamber (not shown) of the cylinder 12, passing through a refrigerant oil path 13a provided in a center of the piston 13.
Being supported to move in the hermetic vessel C, the compressor unit 10 regularly vibrates by the driving of the linear motor 11 and accordingly the oil supply pipe 21 of the oil supply unit 20 reciprocates from side to side by the vibration of the compressor unit 10. Here, the mass 24 located in the oil supply pipe 21 moves due to inertial force produced by the reciprocation of the oil supply pipe 21, so that the oil O located in the bottom of the hermetic vessel C is sucked into the oil supply pipe 21 by pressure difference between the portions formed at both sides of the mass 24. Thus, the oil flowing into the oil supply pipe 21 passes through the first oil path 24a provided in the mass 24 and then a second oil path 23a in the discharge cover 23, and is discharged into an oil pocket P, thereby being supplied to a slide portion formed between the cylinder 12 and the piston 13. Numerals 14 and 15 are a head cover and a valve, respectively. 16 and 17 respectively indicate a coil spring, and 18 and 19 are an external refrigerant suction pipe and a mounting spring, respectively.
However, the oil supply apparatus for the conventional linear compressor has several problems.
First, since the size of the suction valve and the discharge valve that control the suction and the discharge, respectively, of the oil is small, the fabrication and assembly are not easily achieved, thereby decreasing the productivity.
Second, since the suction and discharge valves are compressed and fixed by the compression coil springs supporting the mass, the opening/closing units of the suction and discharge valves are controlled by the compression coil springs, so that the valves can not properly control the suction and discharge of the oil.
Third, since the oil path is provided in the mass, the weight of the mass is reduced as the volume of the oil path so that the compressing force of the mass is reduced and thus the circulation volume of the oil is reduced.